As the development of wireless communication technology, new forms of wireless communication networks are continuously emerging, for example, currently fast-developed Worldwide Interoperability for Microwave Access Forum (WiMax) network, Wireless Local Area Network (WLAN) and so on. Generally, the wireless communication networks include user side devices, Network Access Providers (NAPs) operated by different operators, and Network Service Providers (NSPs). The WiMax network based on the Institute of Electrical and Electronics Engineers (IEEE) 802.16 standard, which can provide higher accessing rate, is used hereinafter as an example for illustration.
Referring to FIG. 1, it is a schematic diagram of the WiMax network reference model in non-roaming situation. In non-roaming situation, an Access Service Network (ASN) 110 is connected to a Connection Service Network (CSN) 120, and a Subscriber Station/Mobile Subscriber Station (SS/MSS) 130 accesses the CSN 120 via the ASN 110.
Referring to FIG. 2, it is a schematic diagram of the WiMax network reference model in roaming situation. In roaming situation, the ASN 110 is connected to a Visited CSN 121, and the Visited CSN 121 is connected to a Home CSN 122. The SS/MSS 130 is authenticated on the Home CSN 122 via the ASN 110 and the Visited CSN 121, and enjoys services provided by the Visited CSN 121 and the Home CSN 122.
Generally, the ASN is operated by the NAP and the CSN is operated by the NSP. In practical deployment, the NAP, a Visited NSP and a Home NSP may be operated by different operators, and the same area may be covered by several ASNs and each ASN may be connected with several NSPs. Currently, in the WiMax network, there are two different deployment modes: one is “NAP+NSP” mode, that is, there is an one-to-one correspondence between the NAPs and the NSPs; and another is “NAP+Sharing” mode, that is, one NAP has a roaming agreement with a plurality of NSPs and shared by the plurality of NSPs.
FIG. 3 shows a possible deployment mode in a WiMax network.
An ASN 111 of a NAP_4 and an ASN 112 of a NAP_6 both have coverage in the same area. A CSN 1201 of a NSP_1, a CSN 1202 of a NSP_2 and a CSN 1203 of a NSP_3 share the ASN 111 of the NAP_4. The ASN 112 of the NAP_6 is bound with a CSN 1204 of a NSP_6. An SS/MSS 131 and an SS/MSS 132 visit the network via the ASNs 111 and 112 respectively.
As for the mode in which the ASN is shared, a user side device may encounter an issue of how to know by which NSPs the current ASN is shared, that is, how to know which NSPs can be used through the current ASN. This is the NSP selection issue in a wireless communication network, that is, how does the network side provide currently available network information for the user side device, so that the user side device can select one NSP from the information of all accessible NSPs at the current position to access the network.
Currently, there are two mechanisms to discovering a NSP in a wireless communication network.
One mechanism is to derive information of an available NSP list mainly by using the “Operator ID” in a DL_MAP message. This mechanism is suitable for not only the “NAP+NSP” mode, but also the “NAP+Sharing” mode. For the “NAP+NSP” mode, it is convenient for the user side device to obtain information of the NSPs supported by the NAP according to the correspondence between the NAPs and NSPs. For the “NAP+Sharing” mode, however, the correspondence between the NAPs and NSPs is more complicated, and it is more difficult to be reflected in time in the user side device after being updated.
Another mechanism is the so-called dynamic NSP discovering mechanism. A Base Station (BS) broadcasts information of the NSPs supported by the current NAP, and the user side device receives relevant broadcasting messages to obtain information of the NSPs during initial scanning. Such a mechanism is more suitable for the “NAP+Sharing” mode, but for the “NAP+NSP” mode, it may cause waste of resources and time.
Moreover, since the broadcasting cycle of the relevant NSP information is long, it takes long time to wait in the NSP discovering. In addition, the relevant messages need to be broadcasted, and sometimes user side devices need to initiatively request for broadcasting messages, which will occupy uplink and downlink air interface resources.
Therefore, how to combine the above two mechanisms in existing wireless communication networks to utilize the network resources effectively is an issue in the art currently.